The present invention relates generally to improvements in segmented mirror assemblies and controls therefor, and more particularly to a novel actuator for precisely controlling the position of a mirror segment in a segmented mirror assembly and for isolating the segment from vibration.
In segmented mirrors it is essential that adjacent segments be positioned accurately relative to each other so that the mirror has an optically coherent reflective surface of predetermined contour. In addition, vibrations in the structure or bulkhead which supports the segmented mirror must be attenuated to eliminate the associated deleterious effects on optical performance of the mirror.
The present invention provides a novel actuator for precisely controlling the position of a segment in a segmented mirror assembly or the like, and for isolating the segment from vibrations occurring in the supporting structure of the mirror assembly. The novel actuator includes a coil assembly attached to the supporting structure, and a magnet mounted on an axially movable shaft disposed between the segment and supporting structure; a small diameter fluid filled bellows is disposed at each end of the shaft and a larger diameter bellows is disposed between each smaller bellows and the supporting structure or segment to provide push-pull capability. A displacement sensor operatively interconnects the supporting structure and shaft to measure the degree of movement of the shaft. The coil assembly produces a linear axial force on the magnet proportional to the electric current in the coil, which force, acting on and compressing one of the small diameter bellows is amplified by fluid forced from the small bellows into the adjacent larger diameter bellows. The amplified force is applied to the supporting structure, thus displacing the segment relative to the bulkhead, resulting in a corresponding small movement of the segment. This motion compresses the larger diameter bellows at the opposite end of the actuator, moving fluid into the smaller diameter bellows. A 20x amplification of the magnetically induced force may be obtained by suitable sizing of the bellows. Two or mroe phased actuators of the invention may be used for the support of each mirror segment.
It is, therefore, a principal object of the present invention to provide an improved actuator for precisely positioning a segment in a segmented mirror assembly or the like.
It is a further object of the invention to provide an improved segmented mirror assembly.
It is yet another object of the invention to provide an actuator assembly for supporting a segment in a segmented mirror assembly which effectively damps vibrations occurring in the supporting structure of the mirror assembly.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.